The metal-oxide-semiconductor (MOS) field-effect transistor (FET) is the fundamental device in semiconductor manufacturing and has been widely used in various types of integrated circuit. Based on the type of main carriers and doping type during fabrication, FETs can be divided into two types: NMOS FET and PMOS FET. The main carriers in NMOS FETs are electrons and the main carriers in PMOS FETs are holes.
The existing techniques provide a method for fabricating MOSFET. The method includes providing a semiconductor substrate, and forming isolation structures on the semiconductor substrate. The semiconductor substrate between isolation structures has active areas; and well areas are formed in the active areas (not labeled). The method also includes doping the surface of the well areas with impurity ions by a first ion implantation process to adjust the threshold voltage of the subsequently formed MOSFET; sequentially forming a gate dielectric layer and a gate electrode on the semiconductor substrate between the isolation structures, where the gate dielectric layer and the gate electrode constitute a gate structure; forming an oxide layer covering the gate structure by an oxidation process; and forming source and drain extension regions in the semiconductor substrate at both sides of the gate structure by a shallow ion implantation process. Further, the method includes using the gate structure as a mask to perform a deep ion implantation process in the well areas at both sides of the gate structure, where the energy and dose of the deep ion implantation is larger than the energy and dose of the shallow ion implantation; and forming a source region and a drain region in the well areas at both sides of the gate structure, where the depth of the source and drain regions is larger than the depth of the source and drain extension regions.
However, the performance of such MOSFET fabricated with existing techniques needs to be improved. The disclosed device structures and methods are directed to solve one or more problems set forth above and other problems.